linux-kernel - Re: Fwd: Potential out-of-bounds in ftrace_regex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAAeHK+wTs3THbh+EVoTm0wqQH8cg2VbT8aKYBX67A385+ohq0w@mail.gmail.com>
Date:	Wed, 9 Oct 2013 14:05:26 +0400
From:	Andrey Konovalov <andreyknvl@...gle.com>
To:	Dave Jones <davej@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andrey Konovalov <andreyknvl@...gle.com>,
	linux-kernel@...r.kernel.org, fweisbec@...il.com, mingo@...hat.com,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Kostya Serebryany <kcc@...gle.com>
Subject: Re: Fwd: Potential out-of-bounds in ftrace_regex_release

I got one more report of a similar bug:

AddressSanitizer: heap-buffer-overflow on address ffff8800205f0e40
Write of size 1 by thread T14005:
 [<ffffffff811e2542>] ftrace_event_write+0xe2/0x130
./kernel/trace/trace_events.c:583
 [<ffffffff8128c497>] vfs_write+0x127/0x2f0 ??:0
 [<ffffffff8128d572>] SyS_write+0x72/0xd0 ??:0
 [<ffffffff818423d2>] system_call_fastpath+0x16/0x1b
./arch/x86/kernel/entry_64.S:629

Allocated by thread T14005:
 [<     inlined    >] trace_parser_get_init+0x28/0x70 kmalloc
./include/linux/slab.h:413
 [<ffffffff811cc258>] trace_parser_get_init+0x28/0x70 ./kernel/trace/trace.c:759
 [<ffffffff811e24d2>] ftrace_event_write+0x72/0x130
./kernel/trace/trace_events.c:572
 [<ffffffff8128c497>] vfs_write+0x127/0x2f0 ??:0
 [<ffffffff8128d572>] SyS_write+0x72/0xd0 ??:0
 [<ffffffff818423d2>] system_call_fastpath+0x16/0x1b
./arch/x86/kernel/entry_64.S:629

The buggy address ffff8800205f0e40 is located 0 bytes to the right
 of 128-byte region [ffff8800205f0dc0, ffff8800205f0e40)

Memory state around the buggy address:
 ffff8800205f0900: rrrrrrrr rrrrrrrr rrrrrrrr rrrrrrrr
 ffff8800205f0a00: rrrrrrrr ........ ........ rrrrrrrr
 ffff8800205f0b00: rrrrrrrr rrrrrrrr rrrrrrrr rrrrrrrr
 ffff8800205f0c00: ........ .......5 rrrrrrrr rrrrrrrr
 ffff8800205f0d00: rrrrrrrr rrrrrrrr rrrrrrrr ........
>ffff8800205f0e00: ........ rrrrrrrr rrrrrrrr rrrrrrrr
                            ^
 ffff8800205f0f00: rrrrrrrr rrrrrrrr rrrrrrrr rrrrrrrr
 ffff8800205f1000: ........ ........ ........ ........
 ffff8800205f1100: ........ ........ ........ ........
 ffff8800205f1200: ........ ........ ........ ........
 ffff8800205f1300: ........ ........ ........ ........
Legend:
 f - 8 freed bytes
 r - 8 redzone bytes
 . - 8 allocated bytes
 x=1..7 - x allocated bytes + (8-x) redzone bytes

This time it was caused by 'parser.buffer[parser.idx] = 0;' in
'ftrace_event_write()', which calls 'trace_get_user()' right before
the bad assignment.

So I still think that the bug is in 'trage_get_user()':
Checking that 'parser->idx < parser->size - 1' is not performed in 'if
(isspace(ch))' section, so 'parser->idx' becomes equal to
'parser->size' after 'parser->buffer[parser->idx++] = ch;'.
(However in 'while (cnt && !isspace(ch))' loop checking is performed.)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/